The coastal surf zone (i.e., the coastal region with depths ranging from zero to ten feet) presents a unique set of challenges in the art of mine clearing. Explosive charges are usually used for clearing lanes within the surf zone. Positioning these charges is too dangerous for dive personnel given the diver's proximity to the mines and the presence of shore hazards. Rocket deployment concepts are under consideration and in development for placing parallel line charges, but this type of approach presents problems related to load capacity, launch platform vulnerability and placement accuracy. Longitudinal and especially lateral placement accuracy is vital because line charge sets must be positioned in parallel to provide a clearance lane. Accordingly, it may be desirable to place mine-clearing charges from an unmanned boat or other watercraft traveling through the surf zone along the path of the desired clearance lane.
While the use of an unmanned boat poses an attractive alternative, wave action in the surf zone remains as an impediment to both boat navigation accuracy and charge placement accuracy. For example, if the lead charge of a set of line charges is simply dropped over the side of the craft, the charge may sink too slowly to the point in the water necessary to pull the remainder of the set into the water thereby increasing longitudinal placement error. Further, wave action acting on the both the boat and the lead charge (as it slowly sinks in the water) increases lateral placement error.
Mine clearing with a boat or other watercraft is most effective only when the boat traverses the entire clearance lane to the dry beach. To insure the boat reaches the beach, high boat speed during charge or line charge deployment is highly desirable because a boat on plane draws much less water. Thus, a fast-moving, shallow draft craft is more likely to traverse the entire clearance lane to the beach. However, sufficiently high boat speed could cause the lead charge to skip along the surface of the water if it were simply dropped over the side of the boat.